Ion twinning allows greater quantum control

Scientists have developed a method involving twinning two atoms in separate locations for the first time, which will potentially allow the simple processing of information in quantum computers.

Researchers at the National Institute of Standards and Technology were able to make two ions of beryllium take turns vibrating while swapping the tiniest measurable units of energy known.

The team were able to exchange just one quantum back and forth, which is a sign that the two ions are ‘coupled’ or linked together while being separated by a distance of about 40 micrometres apart.

“First one ion is jiggling a little and the other is not moving at all; then the jiggling motion switches to the other ion. The smallest amount of energy you could possibly see is moving between the ions,” explains first author Kenton Brown, a NIST post-doctoral researcher.

“We can also tune the coupling, which affects how fast they exchange energy and to what degree. We can turn the interaction on and off.”

It was possible to achieve this by constructing an ion trap cooled to a rather chilly minus 269 C in a liquid helium bath.

While previous attempts have centred around a two level trap the NIST boffins used a single layer, which essentially meant that smaller electrodes could be used to position the ions closer together to create stronger coupling.

With one ion then being frozen to a halt with an ultraviolet laser, the other would be ‘turned on’ with the trap electrode.

To begin the coupling, interaction scientists used electrodes voltages to tune the frequencies of the two ions, thereby nudging them closer together yet vitally still being physically separate.

According to the team the coupling is strongest when the frequencies are closest, with motions becoming liked due to “electrostatic interactions of the positively charged ions, which tend to repel each other.”

With the continued exciting developments towards actually constructing computers that function based on quantum principles, this technique could allow much greater control over the processing of information at this level.

According to the scientists, quantum systems such as the energy transfer of ions could be used to solve massively complex problems, and would – for example – be able to easily break any encryption codes widely used today, while the direct coupling of ions in separate locations could simplify logic operations and help correct processing errors.